increasing dietary fiber
(D) Diverticula are present in over 50% of octogenarians. Most patients remain asymptomatic. They are most common in the sigmoid colon and decrease in frequency in the proximal colon. The relative scarcity of diverticula in underdeveloped nations has led to the hypothesis that low fiber diets result in decreased fecal bulk, narrowing of the colon, and an increased intraluminal pressure to move the small fecal mass. This results in thickening of the muscular coat, and eventually herniations or diverticula of the mucosa at the points where nutrient arteries penetrate the muscularis.